The present invention relates to a rolling support member of a type used for supporting a wide range of items for motion over a support surface. Known rolling support members of this type comprise an outer casing within which is housed a main ball a part of which projects from the casing. In use of such rolling support members the outer casing is fitted into a hole or socket of a support surface in such a way that the projecting part of the main ball is exposed to form a rollable bearing for rolling support of items moving over the support surface. Usually a plurality of such rolling support members are located over the support surface to form a roller plane.
The casing has an axis of symmetry which is usually orthogonal to the support surface when the rolling support member is fitted thereto. The casing is usually formed in two main parts, one of which is received in the socket or hole in the support surface and the other of which defines a shoulder which overlies the edge region surrounding the hole or socket in the support surface and also acts to retain the main ball in the casing. Of course, such rolling support members may alternatively be fitted into an under surface of a body to be carried rollingly on a support surface instead of the other way around as described above.
To retain the casing in the hole or socket in which the member is fitted it is usual to provide resilient tongues on the part of the casing received in the hole or socket.
Rolling members of this type are particularly suitable for conveying items of the most varied types and make it possible to achieve with ease movements of the load in different directions of movement.
To support the main ball in the casing subsidiary balls may be provided between the main ball and a partly spherical bearing surface of the casing.
One known rolling support device of this general type is described in DE-AS No. 22 13 021, in which a releasable interlock device is provided for securing the casing in an opening in a supporting member. The interlock device consists of opposed bolts supported slidably in bores, running at right angles to the axis of symmetry of the rolling support device, on the ends of which bolts act return springs which press the bolts outwards and into engagement with ribs in the opening. The disadvantages of this arrangement are on the one hand the costly and expensive production of the interlock device and on the other hand the fact that the supporting member must have a certain minimum thickness in order to obtain adequate engagement of such bolts. If the supporting member is made of thicker material the opening has to be of special form, so that this type of rolling support device cannot easily be used on all types of supporting member.
Another known rolling support device of this type is described in a pamphlet issued by Rehberg GmbH and entitled "Kugelrollen Typ RE" ("RE type ball rollers"). This device is held in an opening in the supporting member by two spring strips carried by the casing and inclined in the radial direction, relative to the axis of symmetry, towards two opposite points of the casing and fastened to the bottom of the casing or to the walls thereof. When this rolling support device is installed, the spring strips each generate a force at right angles to the axis of symmetry of the device, which acts on the inner surface of the opening in which it is received and thereby frictionally resists withdrawal of the device from the opening. At the same time an additional force can arise which results from the further deformation of the spring strips which occurs when an attempt is made to remove the rolling support device. The force required to remove the rolling support device thus has to overcome the sum of these two forces When the rolling support device is removed from the opening in which it is received this has to be effected by acting from the edge area of the support device by leverage. The disadvantage of this construction is that a secure seating of the device in the supporting member, together with the ability to remove the device without undue difficulty is only obtained for a certain, narrowly defined range of material thickness of the supporting member. If the supporting member is a thin panel the spring strips can snap back to their original length after installation of the rolling support device. The consequences of this are as follows: first the springs no longer exert a radially acting force on the side walls of the opening as a result of this springing back, and the rolling support device thus sits loosely in the opening, merely being held more or less loosely by the ends of the spring strips resting against the rear face of the panel constituting the supporting member. A firm seating therefore no longer exists. With an unfavourable form of spring strip, that is if the strip is relatively long requiring a large degree of deflection, (or looked at another way, if the opening is relatively small) it may even be the case that dismantling of the rolling member is no longer possible without damaging the edge area of the opening in the supporting member, because the ends of the spring strips jam against the rear face of the supporting panel and cannot be deflected inwardly merely by levering up the device from the front face of the panel. On the other hand, if the panel is thicker, and the opening is a relatively narrow bore, the spring strips are pressed very strongly together in this bore, so that deflection practically disappears. As a result, no deformation force arises when withdrawal is attempted. The retaining force thereby becomes dependent mrrely on friction and thus correspondingly low.
Another known rolling support device of this type is discussed in French Patent No. 12 97 185: this device can be held in a receiving opening by a spring locking ring. The disadvantage of this design is that secure retention of the device is only obtained when the supporting member is a sheet or panel of a certain gauge. If the gauge of the panel or sheet is greater than the distance between the face of the device which bears against the panel or sheet and the locking ring, only frictional resistance exists between the device and the opening receiving it. If the panel or sheet is thinner than the bearing face/locking ring separation no axial fixing exists and the device can thus move axially within the bore. If the panel or sheet thickness does correspond to the separation between the bearing face and the locking ring, or is smaller than it, another disadvantage arises in that the device cannot be levered out of the receiving bore without the spring ring first being pressed together.